This invention relates in general to custom-made tools and, more particularly, to an adjustable file handle for files which allows more uniform pressure of the file to be applied against a workpiece.
Prior to our invention most of the files sold throughout the world are not equipped with any type means for holding the file. This presents two major problems. The first and probably the major problem is safety because the hands of the person using the file must grip the sharp edges of the file teeth and the printed end of the tine. Not only are skin puncture wounds caused by this but many accidents occur from striking the fingers against the workpiece. A second significant problem is that usually uneven pressure is applied to the file against a workpiece thereby limiting the usefulness of the file where close tolerances are concerned.
Some files can be purchased which overcome a portion of the first problem because they have a handle which surrounds the tine end of the file. However, one hand must still grip the sharp teeth of the file on the opposite end. Furthermore, this type handle presents another problem not associated with a file without any handle. That is because the handle surrounds the tine end of the file there is danger of some soft material workpiece being damaged by striking of the handle against the soft workpiece. In addition, this type handle does not aid in applying a uniform pressure of the file against a workpiece. Therefore, this type handle has found little usefulness in the home workshops and because it adds to the cost of the file it has not been a great success in the marketplace.
The closest prior art we are aware of which attempts to overcome the above disadvantages of files is a tool called Trimmatool which is manufactured in England and imported into the United States. See page 140 of the January 1979 issue of Popular Science. The Trimmatool has a reversible, replaceable blade with fast-cutting curved teeth on one side and straight teeth on the other. It mounts in a frame with front and rear grips. The rear grip locks in one of two positions either vertical like the handle on a plane or parallel to the blade. In either case your hands are above the tool and out of the way when using the tool on a workpiece. However, the handle used with the Trimmatool is not adjustable and requires the special blade rather than being adaptable to most size files already found in most workshops.